Oscillations in a Magnetized Model Atmosphere with Non-Constant Coefficient of Thermal Conductivity

This paper extends previous investigations of non-adiabatic, oscillatory motions in plane-parallel, gravitationally stratified, magnetized atmospheres by replacing the simple polytropic equilibrium atmosphere with the detailed umbral model atmosphere of Thomas and Scheuer (1982). A normal mode analysis is performed on three cavities defined within the vertical extent of the model. For this work, the coefficient of thermal conductivity is taken to be a function of the temperature and the constant magnetic field is aligned with the direction of gravity. This significantly alters the structure of the eigenspectrum from that of the simpler models using a constant coefficient of thermal conductivity. When evaluated with physical parameters relevant to sunspot umbrae, 5-min and several 3-min oscillations are detected in the cavity from the upper photosphere to the temperature minimum whereas only 3-min oscillations are found in the spatially larger cavity from the upper photosphere to the chromosphere/corona transition region.